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Hepatitis B virus (HBV) is a major cause of liver disease in humans including chronic hepatitis and hepatocellular carcinoma. Domestic cat hepadnavirus (DCH), a novel HBV-like hepadnavirus, was identified in domestic cats in 2018. From 6.5 %-10.8 % of pet cats are viremic for DCH and altered serological markers suggestive of liver damage have been identified in 50 % of DCH-infected cats. DCH DNA has been detected in association with characteristic lesions of chronic hepatitis and with hepatocellular carcinoma in cats, suggesting a possible association. In this study longitudinal molecular screening of cats infected with DCH was performed to determine if DCH can cause chronic infections in cats. Upon re-testing of sera from five DCH-positive animals, 2-10 months after the initial diagnosis, three cats tested negative for DCH on two consecutive occasions using quantitative PCR. Two other cats remained DCH-positive, including an 8-month-old female cat re-tested four months after the initial positive result, and a 9-year-old male cat, which tested positive for DCH on six occasions over an 11-month period. The latter had a history of chronic hepatopathy with jaundice, lethargy and elevated serum alanine transaminase levels (ALT). During the period of observation, DCH titers ranged between 1.64 × 10 5 and 2.09 × 10 6 DNA copies/mL and ALT was persistently elevated, suggesting chronic infection. DCH DNA was not detected in oral, conjunctival, preputial and rectal swabs from the two animals collected at several time points. Long-term (chronic) infection would be consistent with the relatively high number of viremic cats identified in epidemiological investigations, with the possible association of DCH with chronic hepatic pathologies and with what described with HBV in human patients., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Simple Summary: Septic exudates in the body cavities of dogs and cats are considered a critical clinical condition. The current elective diagnostic tools for detecting septic effusion are bacterial culture and fluid cytology. Although culture is considered the gold standard, clinicians may not have access to the results for several days. This may result in a delayed diagnosis of septic effusion, which may have adverse effects on patient outcomes. This study compared the performances of cytology and bacterial culture in the identification of septic exudative body cavity effusions in dogs and cats. The results of our investigation indicated moderate agreement between cytology and microbiology. Cytology and bacterial culture results for exudative body cavity effusions in dogs and cats can be misleading when conducted individually. To improve diagnostic accuracy, these two methodologies should be integrated. The elective test for the determination of the effusions etiopathogenesis is represented by physico-chemical analysis and cytology. Nevertheless, the bacterial culture and antibiotic sensitivity tests are crucial for setting therapy and for the outcome. This study compared cytology with microbiology in the etiologic diagnosis of exudative body cavity effusions in dogs and cats collected from October 2018 to October 2022. All samples underwent aerobic and anaerobic culture and cytology examination. Bacterial identifications were confirmed using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, whereas cytological samples were blindly evaluated either in May Grunwald-Giemsa (MGG) or Gram-stained samples by two board-certified clinical pathologists. A moderate agreement (κ = 0.454) between cytology and bacterial culture was revealed. The sensitivity of the cytological evaluation in our study ranged from 38.5% to 67.9%, and the specificity ranged from 88.9% to 100%, depending on the type of the effusion, so cytology may not be representative of the etiopathogenesis, whereas bacterial culture can misidentify or fail to isolate the correct pathogen for difficult in vitro growing due to the presence of inhibitory substances or contamination. Cytology and bacterial culture results for exudative body cavity effusions in dogs and cats can be misleading if conducted separately, so these two tests should be performed together to increase diagnostic accuracy. [ABSTRACT FROM AUTHOR]

Simple Summary: Domestic cat hepadnavirus (DCH) is a newly identified virus, similar to the hepatitis B virus (HBV). The pathogenicity of DCH in its host needs further investigation. In this report, a case of DCH infection was described in a cat with clinical signs and serum chemistry markers indicative of chronic hepatic disease using a multi-disciplinary diagnostic approach, combining clinical, pathological, virological, and serological information, mirroring the diagnostic approach used for HBV in human patients. Improving the intra-vitam diagnostics for DCH will be useful in developing specific treatment and control strategies. A 3-year-old female stray, shorthair cat, with clinical signs and serum chemistry markers indicative of hepatic disease, was diagnosed with domestic cat hepadnavirus (DCH) infection. Coupling molecular and serological data, the infection was seemingly contextualized into a chronic phase, since IgM anti-core antibodies, a marker of early-stage Hepatitis B Virus (HBV) infection, were not detected. However, the cat possessed IgG anti-core, a common indicator of chronic HBV infection in human patients and did not show seroconversion to the anti-DCH surface antigen, considered protective during HBV infection and associated with long-term protective immunity. On genome sequencing, the DCH strain showed 98.3% nucleotide identity to strains previously identified in Italy. [ABSTRACT FROM AUTHOR]

Domestic cat hepadnavirus (DCH) is an emerging virus related to the hepatitis B virus (HBV). The pathogenic potential of DCH in cats remains to be established. The molecular prevalence of DCH varies widely in the regions investigated so far. The aim of this study was to determine the prevalence, load, and risk factors for DCH detection among cats in Hong Kong, and to generate molecular and epidemiological data on the DCH strains circulating in cats in Hong Kong. DCH DNA was detected using DCH-specific qPCR in 57/513 (11.1%) residual diagnostic blood samples from owned cats. The median viral load was 8.85 × 103 copies/mL of whole blood (range for the 5th to the 95th percentile, 3.33 × 103 to 2.2 × 105 copies per mL). Two outliers had higher viral loads of 1.88 × 107 copies/mL and 4.90 × 109 copies/mL. DCH was detected in cats from 3 months to 19 years of age. Sex, age, neuter status, breed, or elevated serum alanine aminotransferase were not statistically associated with DCH DNA detection. On phylogenetic analysis based on 12 complete genome sequences, the Hong Kong DCH viruses clustered in Genotype A with viruses from Australia and Asia (clade A1), distinct from viruses from Europe (clade A2). Sequence analysis found that DCH has similar epsilon and direct repeat regions to human HBV, suggesting a conserved method of replication. Based on our findings, the DCH strains circulating in Hong Kong are a continuum of the Asiatic strains. [ABSTRACT FROM AUTHOR]

Hepadnaviruses have been identified in several animal species. The hepadnavirus prototype, human hepatitis B virus (HBV), is a major public health problem associated with chronic liver diseases and hepatocellular carcinoma. Recently, a novel hepadnavirus, similar to HBV, was identified in domestic cats. Since several pathogens can be shared between cats and dogs, we hypothesized that dogs could also harbor hepadnaviruses and we tested a collection of canine sera with multiple molecular strategies. Overall, hepadnavirus DNA was identified in 6.3% (40/635) of canine serum samples, although the viral load in positive sera was low (geometric mean of 2.70 × 102 genome copies per mL, range min 1.36 × 102—max 4.03 × 104 genome copies per mL). On genome sequencing, the canine hepadnaviruses revealed high nucleotide identity (about 98%) and similar organization to the domestic cat hepadnavirus. Altered hepatic markers were found in hepadnavirus-positive dogs, although the role of hepadnavirus in canine health remains to be elucidated. [ABSTRACT FROM AUTHOR]

Feline calicivirus (FCV) is a major pathogen of cats associated with either respiratory disease or systemic disease, but its possible role as an enteric pathogen is neglected. Using RT‐PCR, the RNA of FCV was identified in 25.9% (62/239) of stools of cats with enteritis and in 0/58 (0%) of cats without diarrhoea or other clinical signs. Isolates of enteric origin were obtained and a large 3.2‐kb portion of the genome was sequenced, encompassing the 3′ end of the RNA polymerase, the capsid protein precursor and the minor capsid protein. Also, the complete genome sequence of one such strain, the 160/2015/ITA, was determined. Upon sequence analysis, the enteric viruses were found to be genetically heterogeneous and to differ from each other and from isolates of respiratory origin. The enteric isolates were found to be more resistant to low pH conditions, to trypsin and to bile treatment than respiratory isolates. Overall, these findings are consistent with the hypothesis that some FCVs may acquire enteric tropism and eventually act as enteric pathogens. Whether this enteric tropism is maintained stably and whether it may affect, to some extent, the ability of the virus to trigger the classical and/or hypervirulent forms of disease should be assessed. Also, FCV should be included in the diagnostic algorithms of enteric diseases of cats to gain further information about FCV strains displaying enteric pathotype. [ABSTRACT FROM AUTHOR]

The possible role of viruses in feline liver disease has long remained neglected. However, in 2018, an analogue of human hepatitis B virus was identified in cats. Moreover, antibodies for human hepatitis E have been detected consistently at various prevalence rates in cats. Although the correlation between these viruses and the liver injury in cats must be clarified, hepatotropic viruses might represent an increasing risk for feline and public health. [ABSTRACT FROM AUTHOR]

Parvovirus infections in cats have been well known for around 100 years. Recently, the use of molecular assays and metagenomic approaches for virus discovery and characterization has led to the detection of novel parvovirus lineages and/or species infecting the feline host. However, the involvement of emerging parvoviruses in the onset of gastroenteritis or other feline diseases is still uncertain. [ABSTRACT FROM AUTHOR]